Optical Transport Network (OTN) is defined in various ITU Specifications such as, for example, ITU G.709/Y.1331 (December 2009) “Interfaces for the Optical Transport Network (OTN),” the contents of which are herein incorporated by reference. OTN allows network operators to converge networks through seamless transport of the numerous types of legacy protocols while providing the flexibility required to support future client protocols. Optical (i.e., transport) networks and the like (e.g., wavelength division multiplexing (WDM), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Optical Transport Network (OTN), Ethernet, and the like) at various layers are deploying control plane systems and methods. Control planes provide automatic allocation of network resources in an end-to-end manner. Exemplary control planes may include Automatically Switched Optical Network (ASON) as defined in G.8080/Y.1304, Architecture for the automatically switched optical network (ASON) (February/2005), the contents of which are herein incorporated by reference; Generalized Multi-Protocol Label Switching (GMPLS) Architecture as defined in Request for Comments (RFC): 3945 (October/2004) and the like, the contents of which are herein incorporated by reference; Optical Signaling and Routing Protocol (OSRP) from Ciena Corporation which is an optical signaling and routing protocol similar to PNNI (Private Network-to-Network Interface) and MPLS; or any other type control plane for controlling network elements at multiple layers, and establishing connections therebetween.
In OTN control plane networks, a sub-network connection (SNC) for ASON and OSRP or Optical channel Data Unit (ODU) label switched path (LSP) for GMPLS are established at specific rates depending on either the standard Optical channel Data Unit level k (ODUk) rates, where k=0, 1, 2, 2e, 3, 3e2, 4, etc.) or the client rate in the case of ODUflex. Note, SNCs and ODU LSPs (or simply LSPs) can both be referred to as end-to-end paths or end-to-end signaled paths. For packet clients mapped to OTN, the client determines the OTN rate. These rates can be based on standard rates such as 1 Gigabit Ethernet (GbE), 10 GbE, 40 GbE, 100 GbE, etc., or on sub-rates such as a 100 Gb Physical Layer running at 50 Gb/s. In either case, the ODU container must be established at a rate high enough to transport the incoming packets. Service providers offer customers a committed information rate (CIR) and a peak information rate (PIR), where PIR could be a rate provided with best effort availability. These values will be typically defined as part of a service level agreement (SLA). The Layer 2 rate determines the Layer 1 SNC/LSP rate required to carry the service.
During initial establishment of the SNC/LSP, the control plane network nominally has been architected to support the SNC/LSP at a particular rate. However, after a network failure the control plane network may not be able to restore some or all of the affected SNC/LSP's due to limited bandwidth in the network. In addition, network planning and traffic demands are not always predictable, and over-subscription of the network may be required. Conventionally, Layer 1 OTN connections are a fixed size and do not adapt to higher layer CIR/PIR. If the OTN connection size changes, it is typically a result of operator intervention. In the present state of the art, if an OTN circuit goes down, and there is insufficient bandwidth available within the network to replace that circuit, the service remains down, even though there may have sufficient bandwidth to support the underlying net CIR for the Layer 2 services. There are no conventional systems and methods to handle bottlenecks in OTN networks where bandwidth can be dynamically allocated to manage the congestion, while keeping service up on existing circuits.